The present invention generally relates to a method for repairing a pipeline, such as a sewer pipe, by installing a liner inside of the pipeline. Particularly, the invention involves applying a curable resin to the inside walls of the pipeline and installing a flexible lining hose that is coated with a curable resin in the pipeline.
There are numerous pipeline conduits that run underground including water lines, sewer pipes, storm water drains, and the like. These pipelines often must be repaired to fix holes, cracks, and other defects in the line. The pipeline may deteriorate due to ordinary aging, corrosive action of the fluids being transported in the line, unusual environmental conditions, or other reasons. In any event, it is important that the pipeline be mended in order to prevent fluid leakage problems. In some instances, foreign matter may leak through the cracks and into the pipeline conduit. For example, rust, asbestos, and other substances may flow from the surrounding underground environment into the pipeline and contaminate drinking water. In other instances, the water that is being carried through the pipeline conduit may flow outwardly through the cracks leading to a loss of water pressure and other problems.
There are various known methods for renovating existing underground pipelines. Many of these methods employ a lining hose and a calibration hose. For example, Muller, U.S. Pat. No. 4,714,095 discloses a method of salvaging an underground sewer pipe with a lining hose and calibrating hose. The lining hose includes an inner layer which is treated with a first resin, and an outer layer which is not treated with a resin. The lining hose is placed into the pipe conduit. A surface region of a calibrating hose which will contact the inner layer of the lining hose is coated with a second resin. Then, the calibrating hose is introduced into the lining hose. The resins harden so that the lining hose becomes attached to contact surfaces of the calibration hose.
Müller, U.S. Pat. No. 4,770,562 discloses another method of salvaging an underground pipe conduit. A lining hose having an inner layer which is saturated with a resin is used. The lining hose includes an outer layer which is perforated to form flow-through openings for the resin of the inner layer. The lining hose is introduced into the pipe conduit. Then, the lining hose is shaped to conform to the pipe by introducing an auxiliary hose into the lining hose and injecting fluid into the auxiliary hose. The resins harden to form a lining structure in the pipeline. After the curing step, the auxiliary hose can be kept in the lining hose or it can be removed by ropes or cables.
Catallo, U.S. Pat. No. 5,653,555 discloses a method of lining a pipe conduit using multiple curing resins. A lining hose which is coated with a high-strength resin is first positioned inside of the conduit. The lining hose is then expanded into contact with the inside surface of the conduit by inverting a calibration hose. The calibration hose has a layer of corrosion-resistant resin. The high-strength and corrosion-resistant resin layers are cured by the application of a heated fluid. The cured lining hose and calibration hose form a rigid self-supporting structure. The calibration hose is not removed from the liner.
Catallo, U.S. Pat. No. 5,680,885 discloses a method of rehabilitating a damaged pipe conduit using a lining hose and calibration hose. The inner layer of the lining hose is soaked with an excess volume of resin. The calibration hose contains a resin-absorbent layer. The calibration hose is placed in the lining hose and inverted by the application of heated water. After inversion, the resin-absorbent layer of the calibration hose contacts and adheres to the resin coated layer of the lining hose. Upon curing, the calibration hose becomes an integral part of the liner.
Wood, U.S. Pat. No. 5,706,861 discloses a method of lining a section of a pipeline by a “cured in place” system using a lining tube and inflatable bladder. The lining tube is impregnated with a curable synthetic resin and carried into the pipe conduit on an annular inflatable bladder. The lining tube is cured to the pipeline. Then, the bladder is peeled away from the cured lining tube and removed from the pipe conduit by ropes.
Although the above-described conventional methods may be somewhat effective in repairing pipelines, they still suffer from various problems. For example, problems arise concerning the inversion of a felt liner because it is relatively delicate and tends to break or rip during the inversion process. Also, pulling prior art liner tubes around corners is very difficult resulting in fractures in the sealing at such joints. Also, the pipeline joints found at corners and periodically along the length of the pipeline forms voids which cannot be completely filled by the prior art methods. Thus, the prior art methods can do nothing to improve the strength of the pipeline at its joints.
In view of the foregoing, there is a desire for a structural lining process that effectively seals all of the leaks and cracks within a pipeline. It is also desirable to provide a lining process that preserves structural integrity of the liners throughout the length of the pipeline, including tight bend and turn locations within the pipeline. It is also desirable to improve the adhesion between the lining hose inside of the pipeline and the interior walls of the pipeline to ensure integrity of the liner for a permanent installation that does not need periodic repair.